I know this is rather off subject, but everyone here is so knowledible about so many things, I wanted to get your opinions and experiences.

I have a 2001 LB7 Duramax; today, I was approached by a kid from another department who is has a brand new, never installed, MBRP, downpipe back, 4" exhaust system. He said I could have it for $270, and probably a little less just to get it out of his room. In conversation he told me he has the same system on his truck and it gained him about 2 mpgs.

My question is, what will it sound like, is it worth it and will it really improve the mileage that much? I've been reading on some diesel forums and there is no real consensus on the sound. Some people say on an LB7 its just extremely loud and will drone you out running down the highway while others say it sounds great. I know its all personal preference but I don't want it to be loud and obnoxious. I'm not into doing a bunch of useless modifications to my truck, I just want a good, functional work type truck. All the additions I have made since I've gotten the truck have a functional purpose (replace bed rails and leuvered headache rack with a crossbed toolbox, gooseneck ball, edge chip (used for mileage only), 265 all terrain tires for use in fields and pastures, 5th wheel harness in bed. Tow mirrors are next on the list.)

(quoted from post at 23:42:18 12/12/12) I know this is rather off subject, but everyone here is so knowledible about so many things, I wanted to get your opinions and experiences.

I have a 2001 LB7 Duramax; today, I was approached by a kid from another department who is has a brand new, never installed, MBRP, downpipe back, 4" exhaust system. He said I could have it for $270, and probably a little less just to get it out of his room. In conversation he told me he has the same system on his truck and it gained him about 2 mpgs.

My question is, what will it sound like, is it worth it and will it really improve the mileage that much? I've been reading on some diesel forums and there is no real consensus on the sound. Some people say on an LB7 its just extremely loud and will drone you out running down the highway while others say it sounds great. I know its all personal preference but I don't want it to be loud and obnoxious. I'm not into doing a bunch of useless modifications to my truck, I just want a good, functional work type truck. All the additions I have made since I've gotten the truck have a functional purpose (replace bed rails and leuvered headache rack with a crossbed toolbox, gooseneck ball, edge chip (used for mileage only), 265 all terrain tires for use in fields and pastures, 5th wheel harness in bed. Tow mirrors are next on the list.)

Thank you all in advance for your thoughts.

Save your money! There is always some shyster out there trying to beat you out of it with a false promise.

Increasing the airflow though an IC engine can gain horsepower and torque.
Reducing the inlet restriction and a larger exhasut system, adding so called "power elbows", etc that are specially designed to reduce losses etc can help with more air through put. Whether they are cost effective or not is another story. It depends how restrictive the exsisting inlet and exhaust system are. Only a dyno will tell you for sure. Look for data from the part manuafacturer and then be a bit skeptical.

Your engines capacity to process air/fuel into torque/hp has a upper limit. Unless your exhaust is the bottle neck or limiting factor in your complete system you won't see much improvement. And at that mostly at higher rpm, max through put.

Any recommendations increasing mileage on a 6.0 Powerstroke? All of the forums I have found are full of yahoos with giant exhaust pipes and tuners that magically give them 500 HP and 1000 ft-lbs of torque.

I had my computer reprogramed and replaced the air filter to a K&N in the stock box and gained about 3&1/2 miles per gallion after 30,000 miles No exhaust changes were made. I'm at around 19-20 mpg around town in my HD 2004 duramax Silverato double cab. The programing was done with a lap top.

(quoted from post at 04:42:18 12/13/12) I know this is rather off subject, but everyone here is so knowledible about so many things, I wanted to get your opinions and experiences.

I have a 2001 LB7 Duramax; today, I was approached by a kid from another department who is has a brand new, never installed, MBRP, downpipe back, 4" exhaust system. He said I could have it for $270, and probably a little less just to get it out of his room. In conversation he told me he has the same system on his truck and it gained him about 2 mpgs.

My question is, what will it sound like, is it worth it and will it really improve the mileage that much? I've been reading on some diesel forums and there is no real consensus on the sound. Some people say on an LB7 its just extremely loud and will drone you out running down the highway while others say it sounds great. I know its all personal preference but I don't want it to be loud and obnoxious. I'm not into doing a bunch of useless modifications to my truck, I just want a good, functional work type truck. All the additions I have made since I've gotten the truck have a functional purpose (replace bed rails and leuvered headache rack with a crossbed toolbox, gooseneck ball, edge chip (used for mileage only), 265 all terrain tires for use in fields and pastures, 5th wheel harness in bed. Tow mirrors are next on the list.)

Thank you all in advance for your thoughts.

I will guess that the stock exhaust on your truck is most likely dual 3 inch pipes, going into a dual inlet/dual outlet muffler, and then the dual outlet pipes join together into a single, 4 inch pipe.

I will also guess that the stock, dual 3 inch system is more than capable of handling the CFM that your engine will displace, so in essence, that 4 inch exhaust system will do nothing more than increase the noise level and give you bragging rights down at the local pub.

Might gain some mileage. Ive seen a few trucks do decent. Not every truck responds the same to the same mods far as power and mileage.
They are a lil louder then stock if a muffler is used. If its too loud, I end up installing 2 flow threw mufflers.

Best part about bigger exhaust is it will help with egts. Duramax's run HOT. Way hotter then a cummins or a ford - even stock. When I do get to do a duramax exhaust I end up installing a downpipe too. It also makes a good difference in egts and engine temp. It kinda snowballs from there in mods too. Duramax's even run better with after market exhaust manifold and up pipes. Did a '11 LMM, its gets almost 20 driving around town.

$270 is a decent price for exhaust. I can buy exhaust cheaper then that. Few places online will sell it for that much shipped.

Dont forget to run fuel additive - diesel now days is kinda abrasive

Last edited by Matt L on Fri Dec 14, 2012 9:14 pm; edited 1 time in total

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